On Tue, Mar 15, 2022 at 03:21:05PM +0000, Lee, Shawn C wrote:
> On Tuesday, March 15, 2022 8:33 PM, Nikula, Jani <[email protected]>
> wrote:
> >On Mon, 14 Mar 2022, Drew Davenport <[email protected]> wrote:
> >> On Mon, Mar 14, 2022 at 10:40:47AM +0200, Jani Nikula wrote:
> >>> On Sun, 13 Mar 2022, Lee Shawn C <[email protected]> wrote:
> >>> > drm_find_cea_extension() always look for a top level CEA block.
> >>> > Pass ext_index from caller then this function to search next
> >>> > available CEA ext block from a specific EDID block pointer.
> >>> >
> >>> > v2: save proper extension block index if CTA data information
> >>> > was found in DispalyID block.
> >>> > v3: using different parameters to store CEA and DisplayID block index.
> >>> > configure DisplayID extansion block index before search available
> >>> > DisplayID block.
> >>> >
> >>> > Cc: Jani Nikula <[email protected]>
> >>> > Cc: Ville Syrjala <[email protected]>
> >>> > Cc: Ankit Nautiyal <[email protected]>
> >>> > Cc: Drew Davenport <[email protected]>
> >>> > Cc: intel-gfx <[email protected]>
> >>> > Signed-off-by: Lee Shawn C <[email protected]>
> >>> > ---
> >>> > drivers/gpu/drm/drm_displayid.c | 10 +++++--
> >>> > drivers/gpu/drm/drm_edid.c | 53 ++++++++++++++++++---------------
> >>> > include/drm/drm_displayid.h | 4 +--
> >>> > 3 files changed, 39 insertions(+), 28 deletions(-)
> >>> >
> >>> > diff --git a/drivers/gpu/drm/drm_displayid.c
> >>> > b/drivers/gpu/drm/drm_displayid.c index 32da557b960f..31c3e6d7d549
> >>> > 100644
> >>> > --- a/drivers/gpu/drm/drm_displayid.c
> >>> > +++ b/drivers/gpu/drm/drm_displayid.c
> >>> > @@ -59,11 +59,14 @@ static const u8
> >>> > *drm_find_displayid_extension(const struct edid *edid, }
> >>> >
> >>> > void displayid_iter_edid_begin(const struct edid *edid,
> >>> > - struct displayid_iter *iter)
> >>> > + struct displayid_iter *iter, int
> >>> > *ext_index)
> >>>
> >>> Please don't do this. This just ruins the clean approach displayid
> >>> iterator added.
> >>>
> >>> Instead of making the displayid iterator ugly, and leaking its
> >>> abstractions, I'll repeat what I said should be done in reply to the
> >>> very first version of this patch series [1]:
> >>>
> >>> "I think we're going to need abstracted EDID iteration similar to
> >>> what I've done for DisplayID iteration. We can't have all places
> >>> reimplementing the iteration like we have now."
> >>>
> >>> This isn't a problem that should be solved by having all the callers
> >>> hold a bunch of local variables and pass them around to all the
> >>> functions. Nobody's going to be able to keep track of this anymore.
> >>> And this series, as it is, makes it harder to fix this properly later on.
> >>
> >> I missed your original review comment, so apologies for repeating what
> >> you said there already.
> >>
> >> I'd agree that passing a starting index to the displayid_iter_*
> >> functions is probably not the right direction here. More thoughts below.
> >>
> >>>
> >>>
> >>> BR,
> >>> Jani.
> >>>
> >>>
> >>> [1] https://lore.kernel.org/r/[email protected]
> >>>
> >>>
> >>>
> >>> > {
> >>> > memset(iter, 0, sizeof(*iter));
> >>> >
> >>> > iter->edid = edid;
> >>> > +
> >>> > + if (ext_index)
> >>> > + iter->ext_index = *ext_index;
> >>> > }
> >>> >
> >>> > static const struct displayid_block * @@ -126,7 +129,10 @@
> >>> > __displayid_iter_next(struct displayid_iter *iter)
> >>> > }
> >>> > }
> >>> >
> >>> > -void displayid_iter_end(struct displayid_iter *iter)
> >>> > +void displayid_iter_end(struct displayid_iter *iter, int
> >>> > +*ext_index)
> >>> > {
> >>> > + if (ext_index)
> >>> > + *ext_index = iter->ext_index;
> >>> > +
> >>> > memset(iter, 0, sizeof(*iter));
> >>> > }
> >>> > diff --git a/drivers/gpu/drm/drm_edid.c
> >>> > b/drivers/gpu/drm/drm_edid.c index 561f53831e29..78c415aa6889
> >>> > 100644
> >>> > --- a/drivers/gpu/drm/drm_edid.c
> >>> > +++ b/drivers/gpu/drm/drm_edid.c
> >>> > @@ -3353,28 +3353,27 @@ const u8 *drm_find_edid_extension(const struct
> >>> > edid *edid,
> >>> > return edid_ext;
> >>> > }
> >>> >
> >>> > -static const u8 *drm_find_cea_extension(const struct edid *edid)
> >>> > +static const u8 *drm_find_cea_extension(const struct edid *edid,
> >>> > + int *cea_ext_index, int
> >>> > *displayid_ext_index)
> >>
> >> As discussed above, passing both indices into this function may not be
> >> the best approach here. But I think we need to keep track of some kind
> >> of state in order to know which was the last CEA block that was
> >> returned, and thus this function can return the next one after that,
> >> whether it's in the CEA extension block or DisplayID block.
> >
> >Per DisplayID v1.3 Appendix B: DisplayID as an EDID Extension, it's
> >recommended that DisplayID extensions are exposed after all of the CEA
> >extensions.
> >
> >I think it should be fine to first iterate over all CEA extensions across
> >the EDID, followed by iterating over all the DisplayID extensions. No need
> >to keep track of the order between CEA and DisplayID, as the former should
> >precede the latter.
> >
>
> Refer to "DisplayID extensions are exposed after all of the CEA extensions".
> It looks to me patch v5 is able to support this. And did not touch DisplayID
> iterator.
> https://patchwork.freedesktop.org/series/100690/#rev5
Patch v5 does not iterate over all the DisplayID extensions, and it has
the previously mentioned problem about resulting in a possible infinite
loop when depending on ext_index to iterate over the CEA extensions.
>
> >> What do you think of using the pointer returned from this function as
> >> that state? The caller could pass in a u8* that was returned from a
> >> previous call. This function would iterate through the extension
> >> blocks and skip the CEA blocks it finds until it finds the passed in
> >> pointer, and then return the next one after (or NULL).
> >>
> >> An alternative might be to create a linked list of ptrs to the edid
> >> extension blocks, and allow a caller to iterate over them in whatever
> >> way they need, but I'm not sure how useful that is elsewhere.
> >
> >I think the main problem here is trying to hack a for loop around
> >drm_find_cea_extension() and drm_find_edid_extension(), and duplicating that
> >all over the place, without adding more structure or abstractions.
> >
> >Contrast with displayid_iter_edid_begin(), displayid_iter_for_each(), and
> >displayid_iter_end() and their usage. They hide all the complexity of
> >looping across DisplayID data blocks inside EDID extensions, and none of the
> >users need to be aware of that complexity. All the state is hidden in struct
> >displayid_iter, and the users don't need to look inside. No allocations, no
> >linked lists.
> >
> >I think it's particularly bad to have the changes here break the
> >abstractions in displayid_iter_*, especially because they should be usable
> >for pure DisplayID 2.0 *without* an EDID block structure. They'll just need
> >a displayid_iter_begin() for pure DisplayID and some internal changes.
> >
> >Looking at the usage, the iteration should probably be done at the CEA data
> >block level, something like this:
> >
> > struct cea_iter iter;
> > const struct cea_block *block;
> >
> > cea_iter_edid_begin(edid, &iter);
> > cea_iter_for_each(block, &iter) {
> > /* ... */
> > }
> > cea_iter_end(&iter);
> >
> >This would replace cea_db_offsets() and for_each_cea_db(), and would iterate
> >across the all CEA and DisplayID extensions in the entire EDID.
> >
> >This looks usable, and then you'd start figuring out how to implement that,
> >instead of trying to retrofit all the existing usages to abstractions that
> >don't cut it. You'll probably need an EDID extension iterator too, and then
> >use that and __displayid_iter_next() within
> >cea_iter_for_each() i.e. you'd embed the edid_iter and displayid_iter within
> >struct cea_iter. Exhaust the former first, and then the latter.
> >
> >
> >BR,
> >Jani.
> >
>
> Hi Jani, Drew, thank you all for your comment! Agree that edid driver may need
> abstracted EDID iteration similar to what you did for DisplayID iteration.
> It will need a lot of code changes in drm driver.
>
> But, we have a tight schedule and have to meet HDMI 2.1 compliance test
> requirement.
> Do you think this series can be a short term solution to pass HDMI CTS test?
> And we can have another long term plan to work on your opinion to modify
> the iterator and make edid driver more efficient and easier to maintain.
>
> Best regards,
> Shawn
>
> >
> >>
> >>> > {
> >>> > const struct displayid_block *block;
> >>> > struct displayid_iter iter;
> >>> > const u8 *cea;
> >>> > - int ext_index = 0;
> >>> >
> >>> > - /* Look for a top level CEA extension block */
> >>> > - /* FIXME: make callers iterate through multiple CEA ext blocks?
> >>> > */
> >>> > - cea = drm_find_edid_extension(edid, CEA_EXT, &ext_index);
> >>> > + /* Look for a CEA extension block from ext_index */
> >>> > + cea = drm_find_edid_extension(edid, CEA_EXT, cea_ext_index);
> >>> > if (cea)
> >>> > return cea;
> >>> >
> >>> > /* CEA blocks can also be found embedded in a DisplayID block */
> >>> > - displayid_iter_edid_begin(edid, &iter);
> >>> > + displayid_iter_edid_begin(edid, &iter, displayid_ext_index);
> >>> > displayid_iter_for_each(block, &iter) {
> >>> > if (block->tag == DATA_BLOCK_CTA) {
> >>> > cea = (const u8 *)block;
> >>> > break;
> >>> > }
> >>> > }
> >>> > - displayid_iter_end(&iter);
> >>> > + displayid_iter_end(&iter, displayid_ext_index);
> >>> >
> >>> > return cea;
> >>> > }
> >>> > @@ -3643,10 +3642,10 @@ add_alternate_cea_modes(struct drm_connector
> >>> > *connector, struct edid *edid)
> >>> > struct drm_device *dev = connector->dev;
> >>> > struct drm_display_mode *mode, *tmp;
> >>> > LIST_HEAD(list);
> >>> > - int modes = 0;
> >>> > + int modes = 0, cea_ext_index = 0, displayid_ext_index = 0;
> >>> >
> >>> > /* Don't add CEA modes if the CEA extension block is missing */
> >>> > - if (!drm_find_cea_extension(edid))
> >>> > + if (!drm_find_cea_extension(edid, &cea_ext_index,
> >>> > +&displayid_ext_index))
> >>> > return 0;
> >>> >
> >>> > /*
> >>> > @@ -4321,11 +4320,11 @@ static void
> >>> > drm_parse_y420cmdb_bitmap(struct drm_connector *connector, static
> >>> > int add_cea_modes(struct drm_connector *connector, struct edid
> >>> > *edid) {
> >>> > - const u8 *cea = drm_find_cea_extension(edid);
> >>> > - const u8 *db, *hdmi = NULL, *video = NULL;
> >>> > + const u8 *cea, *db, *hdmi = NULL, *video = NULL;
> >>> > u8 dbl, hdmi_len, video_len = 0;
> >>> > - int modes = 0;
> >>> > + int modes = 0, cea_ext_index = 0, displayid_ext_index = 0;
> >>> >
> >>> > + cea = drm_find_cea_extension(edid, &cea_ext_index,
> >>> > +&displayid_ext_index);
> >>> > if (cea && cea_revision(cea) >= 3) {
> >>> > int i, start, end;
> >>> >
> >>> > @@ -4563,6 +4562,7 @@ static void drm_edid_to_eld(struct drm_connector
> >>> > *connector, struct edid *edid)
> >>> > const u8 *cea;
> >>> > const u8 *db;
> >>> > int total_sad_count = 0;
> >>> > + int cea_ext_index = 0, displayid_ext_index = 0;
> >>> > int mnl;
> >>> > int dbl;
> >>> >
> >>> > @@ -4571,7 +4571,7 @@ static void drm_edid_to_eld(struct drm_connector
> >>> > *connector, struct edid *edid)
> >>> > if (!edid)
> >>> > return;
> >>> >
> >>> > - cea = drm_find_cea_extension(edid);
> >>> > + cea = drm_find_cea_extension(edid, &cea_ext_index,
> >>> > +&displayid_ext_index);
> >>> > if (!cea) {
> >>> > DRM_DEBUG_KMS("ELD: no CEA Extension found\n");
> >>> > return;
> >>> > @@ -4657,9 +4657,10 @@ int drm_edid_to_sad(struct edid *edid,
> >>> > struct cea_sad **sads) {
> >>> > int count = 0;
> >>> > int i, start, end, dbl;
> >>> > + int cea_ext_index = 0, displayid_ext_index = 0;
> >>> > const u8 *cea;
> >>> >
> >>> > - cea = drm_find_cea_extension(edid);
> >>> > + cea = drm_find_cea_extension(edid, &cea_ext_index,
> >>> > +&displayid_ext_index);
> >>> > if (!cea) {
> >>> > DRM_DEBUG_KMS("SAD: no CEA Extension found\n");
> >>> > return 0;
> >>> > @@ -4719,9 +4720,10 @@ int drm_edid_to_speaker_allocation(struct
> >>> > edid *edid, u8 **sadb) {
> >>> > int count = 0;
> >>> > int i, start, end, dbl;
> >>> > + int cea_ext_index = 0, displayid_ext_index = 0;
> >>> > const u8 *cea;
> >>> >
> >>> > - cea = drm_find_cea_extension(edid);
> >>> > + cea = drm_find_cea_extension(edid, &cea_ext_index,
> >>> > +&displayid_ext_index);
> >>> > if (!cea) {
> >>> > DRM_DEBUG_KMS("SAD: no CEA Extension found\n");
> >>> > return 0;
> >>> > @@ -4815,8 +4817,9 @@ bool drm_detect_hdmi_monitor(struct edid *edid)
> >>> > const u8 *edid_ext;
> >>> > int i;
> >>> > int start_offset, end_offset;
> >>> > + int cea_ext_index = 0, displayid_ext_index = 0;
> >>> >
> >>> > - edid_ext = drm_find_cea_extension(edid);
> >>> > + edid_ext = drm_find_cea_extension(edid, &cea_ext_index,
> >>> > +&displayid_ext_index);
> >>> > if (!edid_ext)
> >>> > return false;
> >>> >
> >>> > @@ -4854,8 +4857,9 @@ bool drm_detect_monitor_audio(struct edid *edid)
> >>> > int i, j;
> >>> > bool has_audio = false;
> >>> > int start_offset, end_offset;
> >>> > + int cea_ext_index = 0, displayid_ext_index = 0;
> >>> >
> >>> > - edid_ext = drm_find_cea_extension(edid);
> >>> > + edid_ext = drm_find_cea_extension(edid, &cea_ext_index,
> >>> > +&displayid_ext_index);
> >>> > if (!edid_ext)
> >>> > goto end;
> >>> >
> >>> > @@ -5178,8 +5182,9 @@ static void drm_parse_cea_ext(struct
> >>> > drm_connector *connector,
> >>> > struct drm_display_info *info = &connector->display_info;
> >>> > const u8 *edid_ext;
> >>> > int i, start, end;
> >>> > + int cea_ext_index = 0, displayid_ext_index = 0;
> >>> >
> >>> > - edid_ext = drm_find_cea_extension(edid);
> >>> > + edid_ext = drm_find_cea_extension(edid, &cea_ext_index,
> >>> > +&displayid_ext_index);
> >>> > if (!edid_ext)
> >>> > return;
> >>> >
> >>> > @@ -5311,12 +5316,12 @@ static void drm_update_mso(struct drm_connector
> >>> > *connector, const struct edid *e
> >>> > const struct displayid_block *block;
> >>> > struct displayid_iter iter;
> >>> >
> >>> > - displayid_iter_edid_begin(edid, &iter);
> >>> > + displayid_iter_edid_begin(edid, &iter, NULL);
> >>> > displayid_iter_for_each(block, &iter) {
> >>> > if (block->tag == DATA_BLOCK_2_VENDOR_SPECIFIC)
> >>> > drm_parse_vesa_mso_data(connector, block);
> >>> > }
> >>> > - displayid_iter_end(&iter);
> >>> > + displayid_iter_end(&iter, NULL);
> >>> > }
> >>> >
> >>> > /* A connector has no EDID information, so we've got no EDID to
> >>> > compute quirks from. Reset @@ -5516,13 +5521,13 @@ static int
> >>> > add_displayid_detailed_modes(struct drm_connector *connector,
> >>> > struct displayid_iter iter;
> >>> > int num_modes = 0;
> >>> >
> >>> > - displayid_iter_edid_begin(edid, &iter);
> >>> > + displayid_iter_edid_begin(edid, &iter, NULL);
> >>> > displayid_iter_for_each(block, &iter) {
> >>> > if (block->tag == DATA_BLOCK_TYPE_1_DETAILED_TIMING ||
> >>> > block->tag == DATA_BLOCK_2_TYPE_7_DETAILED_TIMING)
> >>> > num_modes +=
> >>> > add_displayid_detailed_1_modes(connector, block);
> >>> > }
> >>> > - displayid_iter_end(&iter);
> >>> > + displayid_iter_end(&iter, NULL);
> >>> >
> >>> > return num_modes;
> >>> > }
> >>> > @@ -6164,12 +6169,12 @@ void drm_update_tile_info(struct
> >>> > drm_connector *connector,
> >>> >
> >>> > connector->has_tile = false;
> >>> >
> >>> > - displayid_iter_edid_begin(edid, &iter);
> >>> > + displayid_iter_edid_begin(edid, &iter, NULL);
> >>> > displayid_iter_for_each(block, &iter) {
> >>> > if (block->tag == DATA_BLOCK_TILED_DISPLAY)
> >>> > drm_parse_tiled_block(connector, block);
> >>> > }
> >>> > - displayid_iter_end(&iter);
> >>> > + displayid_iter_end(&iter, NULL);
> >>> >
> >>> > if (!connector->has_tile && connector->tile_group) {
> >>> > drm_mode_put_tile_group(connector->dev,
> >>> > connector->tile_group);
> >>> > diff --git a/include/drm/drm_displayid.h
> >>> > b/include/drm/drm_displayid.h index 7ffbd9f7bfc7..15442a161c11
> >>> > 100644
> >>> > --- a/include/drm/drm_displayid.h
> >>> > +++ b/include/drm/drm_displayid.h
> >>> > @@ -150,11 +150,11 @@ struct displayid_iter { };
> >>> >
> >>> > void displayid_iter_edid_begin(const struct edid *edid,
> >>> > - struct displayid_iter *iter);
> >>> > + struct displayid_iter *iter, int
> >>> > *ext_index);
> >>> > const struct displayid_block *
> >>> > __displayid_iter_next(struct displayid_iter *iter); #define
> >>> > displayid_iter_for_each(__block, __iter) \
> >>> > while (((__block) = __displayid_iter_next(__iter))) -void
> >>> > displayid_iter_end(struct displayid_iter *iter);
> >>> > +void displayid_iter_end(struct displayid_iter *iter, int
> >>> > +*ext_index);
> >>> >
> >>> > #endif
> >>>
> >>> --
> >>> Jani Nikula, Intel Open Source Graphics Center
> >
> >--
> >Jani Nikula, Intel Open Source Graphics Center
